The field of providing products with built-in antimicrobial protection has grown tremendously over the past several years. What once started out as a premium or novel option for high-end consumer products and medical devices has now grown into a mainstream characteristic found in many consumer products. Consumers can go to any home improvement center and see dozens if not hundreds of products that claim some degree of resistance to microbiological growth or contamination. Some major retailers have specific sections devoted to such antimicrobial products.
Antibacterial products have been introduced into plastics, textiles, liquids, metal coatings, and an array of other types of materials. However, there remain several areas of consumer and commercial products in which development of commercially viable antimicrobial products has proven difficult. One such area is ceramic coatings.
Ceramic coatings are commonly used in products that store, treat, or transport water and liquid waste. Ceramic toilets, urinals, bidets, bathroom basins, flooring tiles and other bathroom fixtures are probably the most common example of such products.
Ceramic products used to collect and transport water are often stained by scum and films of biologic origin (e.g., bacteria, fungus, mold, mildew). To date, the primary method of removing biological scum and film from these ceramic products has been to abrade the ceramic surface in the presence of topical cleaning agent. This process is time consuming and provides little or no protection against future growth. Some cleaning agents can damage the surface of the ceramic product. Therefore there is great interest in the development of ceramic coatings that have built-in protection against the growth and proliferation of microbes.
A few such built-in antimicrobial coatings are described in the ceramic literature but they have not seen commercial success. Existing technologies are somewhat limited. For example, the high temperatures used in ceramic firing processes typically preclude the use of organic antimicrobial agents. Inorganic silver-based antibacterials are too expensive. Zinc oxide is known as having antimicrobial characteristics and has been used in the preparation of ceramic glazing compositions. However, known ceramic glazing compositions that rely solely upon zinc oxide as an antimicrobial agent have not shown antimicrobial efficacy sufficient for control of microbial growth and proliferation on ceramic surfaces. Accordingly, there is a need for a low-cost ceramic coating that has built-in antimicrobial protection.
Thus, one object of the present invention is to provide a new and useful antimicrobial ceramic coating that can impart antimicrobial characteristics in a wide range of products.
A still further object of the invention is to provide this ceramic coating at a cost that is acceptable to the marketplace. Furthermore, this antimicrobial ceramic coating should be safe to humans, exhibit commercially acceptable antimicrobial properties, and most importantly, be compatible with existing ceramic production processes.
These and other objects are achieved by the claimed invention, which in one embodiment is an antimicrobial ceramic glazing composition comprising a quantity of zinc borate sufficient to achieve a commercially acceptable level of antimicrobial efficacy. In preferred embodiments this ceramic glazing composition also comprises a quantity of zinc oxide.
In a further embodiment, the invention is a ceramic article that exhibits antimicrobial properties. The ceramic article according to the invention has at least one surface and a glaze on a portion of that surface. The glaze comprises a quantity of zinc borate sufficient to achieve a commercially acceptable level of antimicrobial efficacy. In preferred embodiments this ceramic glazing composition also comprises a quantity of zinc oxide.
In yet another embodiment, the invention is a method of making an antimicrobial ceramic glaze and a method of making a ceramic article comprising the antimicrobial ceramic glaze.